The primary purpose of this R03 small research grant is to provide short-term support for the PI to further develop a promising ongoing research project on the function of Gene 33 in ischemic cardiomyopathy. Our goal is to develop the project into a full size research program that can successfully compete for R01 support. This grant would also help the PI to develop a research career on age-related heart diseases. The Molecular Cardiology Research Institute at the Tufts-New England Medical Center provides an excellent physical and intellectual environment for perusing research on cardiovascular diseases. Cardiomyocyte apoptosis is closely linked to age-related heart conditions, such as myocardial infarction, ischemia/reperfusion injury and heart failure. Evidence shows that cardiomyocyte apoptosis involves the dysfunctional regulation of multiple intracellular signaling pathways, which function to maintain a balance between apoptotic and survival signals. Despite numerous research efforts, the molecular mechanisms behind cardiomyocyte apoptosis in response to ischemic insults are still poorly understood. Published studies have focused mostly on conventional mediators of apoptosis. Transcriptionally induced mediators of cardiomyocyte apoptosis are much poorly understood. These mediators could be more relevant to cardiomyocyte apoptosis in chronic disease conditions related to the aging process. The focus of the proposed study will be on the role of Gene 33 in mouse cardiac ischemia. We have discovered that Gene 33 is a mediator of cardiomyocyte apoptosis induced by hypoxia and hypoxia/reoxygenation. Gene 33 is transcriptionally induced by hypoxia in cardiomyocytes and by ischemic stresses in murine hearts. Gene 33 inhibits AKT and ERK activition mediated by ErbB and IGF-1 receptor tyrosine kinase signaling. We also find that over- expression of Gene 33 in neonatal rat cardiomyocytes strongly induces apoptosis. These results suggest a significant role of Gene 33 in cardiomyocyte apoptosis in vivo. We hypothesize that Gene 33 mediates cardiomyocyte apoptosis in response to ischemic injury in vivo. We accordingly propose two specific aims to test our hypothesis: 1) Characterize the effect of gene 33 overexpression on the mouse heart. 2) Explore how disruption of gene 33 influences cardiomyocyte apoptosis and cardiac function following ischemic injury to the mouse heart. We believe that this study will provide significant new insight into the understanding of cardiomyocyte apoptosis and ischemic cardiomyopathy and contribute to identifying novel therapeutic targets in age-related heart diseases. Relevance: This research project studies a potentially important molecular mediator of ischemic cardiomyopathy. Ischemic cardiomyopathy is a heart condition (caused by restriction of blood flow to the heart) that is especially prevalent in the aging population and affects millions of people in this country. This study would provide significant new insight into understanding the mechanisms of the disease and contribute to identification of novel therapeutic targets. [unreadable] [unreadable] [unreadable]